Piston



April 21, 1931. w MccOY 1,802,180

PISTON Filed Oct: 18, 1929 2 Sheets-Sheet 1- w '4 T: i :IrSEj -L/ INVENTOR mum, C.Mc CA ATTORNEYS W. C. M COY A ril 21, 1931.

PISTON Filed Oct. 18, 1929 2 Sheets-Sheet 2 nlT fL ru Ii III III I! INVENTOR IVilliam 6. Ala Coy BY 8. w ATTORNEYS Patented Apr. 21, 1931 UNITED STATES PATENT OFFICE WILLIAM C. MCCOY, OF SHAKER- HEIGHTS, OHIO, ASSIGNOB TO THE CLEVELAND TRUST COMPANY, OF CLEVELAND, OHIO, A. CORPORATION OF OHIO PISTON Application filed October 18, 1929. Serial No. 400,478.

This invention relates to pistons for internal combustion engines and particularly to composite pistons composed of metals of different thermal expansibility and is a continuation in part of my copending application Serial No. 143,87 9, filed Oct. 25, 1926.

The present invention has for its object to rovide a skirt which is readily compressible in response to externally applied pressure and which is normally held by thermally responsive internal supporting means to substantially the diameter of the cylinder.

A further object is to provide a piston having a compressible skirt which is entirely separate from the head and wrist p1n bosses and which is supported by struts extending laterally from the bosses to opposite portions ofthe skirt and providing a support for the skirt which is relatively rigid on one side and flexible on the other so that a rigid support is provided for the working face subjected to ressure on the explosion stroke and a yieldmg support is provided for the working face which is subjected to-pressure on the compression stroke.

With the above and other objects in view, the invention may be said to comprise a piston as illustrated in the aceompanyin drawings hereinafter described and partlcularly set forth in the appended claims, together with such variations and modifications thereof as will be pparent to one skilled in the art to which the invention appertains.

Reference should be had to the accompanying drawings forming a part of this specification in which:

Figure 1 is a side elevation of a piston with a portion of the skirt broken away and shown in section to show the attachment of the supporting member to the'skirt.

Fig. 2 is a side elevation of the piston with a portion broken away and shown in axial section.

Fig. 3 is a bottom plan view of the piston.

Fig.4 is a bottom plan view of the piston having a slightly modified skirt supporting member.

Fig. 5 is a bottom plan view showing a further modification.

Fig. 6 shows one of the strut plates in side elevation.

Fig. 7 is a side elevation of the piston shown in Fig. 5.

Fi 8 is a side elevation of a piston embodylng a 'further modification of the invention.

Fig. 9 is a bottom plan view of the piston shown in Fig. 8.

Fig. 10 is a side elevation of the figures shown in Figs. 8 and 9, with a portion broken away and shown in axial section.

As illustrated in Figs. 1, 2 and 3 of the drawing, the piston is provided with a head 1 of conventional form to which wrist pin bosses 2 are integrall connected by means of arms 3 integral wit 1 the head and extending downwardly therefrom inwardly of the periphery of the head. The piston is also provided with a cylindrical skirt 4 which is entirely separate from both the head and wrist pin bosses, the skirt being provided on opposite sides thereof with openings 5 extending downwardly from the top of the skirt and of suflicient width to accommodate the wrist pin bosses. On opposite sides of the wrist pin bosses, the skirt is provided with working faces 6 and 7 which extend the full length of the skirt, one working face being subjected to pressure on the explosion stroke and the other being subjected to pressure upon the compression stroke of the piston. The skirt is preferably compressible under externally applied pressure and to provide the desired flexibility in the skirt, a slot is provided from the lower edge of the skirt to the bottom of one of the openings 5.

The portions of the skirt on opposite sides of the slot 8 may be connected b means of an integral flexible web 9 exten ing across the slot on the interior of the skirt. The skirt is supfported from the wrist pin bosses by means 0 a metal plate or strip 10, prefera ly of steel which is of a width somewhat greater than the diameter of the wrist pin bosses and which is provided with apertures 11 adapted to register with the apertures of the bosses. One of the apertures 11 is adjacent one end of the supporting strip and the other is located at a distance from the o posite end. The strip 10 is bent so that t e portions thereof in which the apertures 11 are formed are disposed in parallel relation with the openings thereof in alinement. In forming the piston, these portions of the strip are cast into thewrist pin bosses, the apertures being provided with serrations 12 at the periphery which are embedded in the metal of the bosses around the wrist pin openings. The portion of the strip 10 between the apertures 11 is bowed to engage the interior of the skirt centrally of one of the'working faces and midway between the apertures. The strip is provided with apertures 13 and longitudinal slots 15 which receive the metal of the strip, the apertured and slotted bowed portion of the strip being embedded in the metal of the skirt in the casting of the piston. The end of the strip pro- 'ecting from one of the portions thereof emedded in a wrist pin boss is bent to a curvature corresponding to the curvature of the bowed portion on the opposite side of the bosses and is provided with apertures 16 and longitudinal slots 17 to receive the metal of the skirt, this end of the strip being embedded in the skirt diametrically opposite the connection of the skirt to the intermediate bowed portion of the strip and centrally of the opposite working face.

As will be readily seen in Fig. 3 of the drawings, the intermediate bowed portion of the strip provides outwardly converging struts 18 and 19 from the two wrist pin bosses to the central zone of one of the working faces of the piston, and the end of the strip provides a single strut 20 from one of the bosses to the opposite working face of the skirt. The side of the piston supported by the struts 18 and 19 is supported with relative rigidity, whereas the opposite portion which is supported by the single strut 20, may yield in response to radial thrust. The rigidly supported working face 6 is the face subjected to thrust on the explosion stroke of the piston and the opposite face 7 is the face subjected to the thrust on the compression stroke. The thrusts exerted on the explosion stroke being much greater than the thrusts exerted on the compression stroke, the advantage of a stronger and more rigid support for this working face will be apparent.

In Fig. 4 of the drawing, there is shown a. piston identical with that shown in Figs. 1, 2 and 3, except that the steel supporting strip is formed to provide straight converging struts 21 from the bosses to one of the working faces and a straight laterally inelined strut 22 from one of the bosses to the opposite working face, the straightstruts providing a somewhat more rigid support for the face of the piston subjected to pressure on the explosion stroke.

In Figs. 5, 6 and 7 of the drawing, a modifield construction is shown in which one of the struts is formed by a steel plate 23 having an aperture 24 registering with the aperture of the boss and serrations 25 embedded in the metal of the boss around its aperture. The plate 23 is disposed at right angles to the axis of the boss and projects laterally therefrom to the interior of the skirt, where it has a'serrated edge 26 embedded in the metal of the skirt. The second strut is in the form of a steel plate 27 which has a serrated aperture corresponding to the aperture 24 of the plate 23 embedded in the metal of the opposite wrist pin boss of the piston. The late 27, however, projects from both sides 0 the wrist pin boss, one end 28 extending parallel with the plate 23 and having serrated edges.

29 embedded in the metal of the skirt on the same side of the wrist pin bosses. The opposite projecting end portion 30 of the plate 27 is bent laterall and has a serrated edge 31 embedded in the metal of the skirt. It would be apparent that the plates 23 and 27 provide a rigid support for one working face of the piston and that the laterally bent end 30 of the plate 27 provides a yielding strut for supporting the opposite working face of the skirt.

In Figs. 8, 9 and 10, there is shown a modification in which the head 32 is provided with integral bosses 33 and the skirt 34 is connectedto the bosses by means of integral arms 35 extending from the undersides of the bosses to the interior of the skirt adjacent its lower end. The skirt, however, is otherwise unattached to the head and bosses and is made flexible by means of a slot 36 extend ing upwardly from the bottom thereof to the bottom of the boss receiving 0 ening of the skirt, the adjoining portions 0 the skirt being connected across the slot by an integral flexible web 37 inside of the skirt. The skirt is additionally supported by means of steel strut plates 38 and 39 extending at right angles from the bosses across the tops thereof to the interior of the skirt to provide a rigid support for one working face, one of the plates having a laterally bent arm 40 attached to the interior of the skirt to provide a yielding support for the opposite working face, both plates having recessed and serrated lower edges embedded in the metal of the wrist pin bosses.

It will be apparent that the present invention provides a piston which has a flexible skirt which can be readily compressed by externally applied pressure to conform to the interior of the cylinder and which has ample rigidity to resist distortion due to heavy thrusts exerted thereon during the explosion stroke, the flexibility being rovided mainly in the portion of the skirt su jected to thrust only during the compression stroke. The steel or other metal of which the strut plates are composed preferably has a coefficient of expansion less than that of the metal of the skirt and serves to hold the skirt to substantially the diameter of the cylinder in which the piston works.

Furthermore, it is to be understood that the particular form of apparatus shown and de scribed, and the particular procedure set forth, are presented for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as defined in the appended claims.

What I claim is:

1. A piston comprising a head, a pair of wrist pin bosses integral with the head, a skirt having oppositely disposed bearing portions, a transverse strut of less thermally expansive material than the head connected to one boss and to each of said skirt portions, a second transverse strut connecting the other boss with one only of the skirt portions, said struts being relatively flexible laterally.

2. A piston comprising a head, wrist pin bosses integral with the head, a flexible skirt separate from the head and bosses, struts attached to said bosses and extending transversely thereof, one of said struts being attached to the skirt on opposite sides of the boss and the other of said struts being attached to the skirt at one side only.

3. A piston comprising a head, wrist pin bosses integral with the head. a flexible skirt separate from the head and bosses, struts of a metal having a lower coeflicient of expansion than the skirt fixed to said bosses and extendin tiansversely thereof, one of said struts l ieing attached to the skirt on opposite sides of the bosses and the other strut being attached to the skirt at one side only.

4-. A piston comprising a head, wrist pin bosses integral with the head, a flexible skirt separate from the head and bosses, a supporting member attached adjacent one end thereof to one of the bosses and at a point spaced from the opposite end to the other boss, said memberhaving an intermediate bowed portion attached to the skirt at one side of said bosses and a laterally bent end portion extending from the last mentioned boss and attached to the skirt at the opposite side of said bosses.

5. A piston comprising a head, a pair of wrist pin bosses integral with the head, a skirt having oppositely disposed bearing portions, a transverse strut of less thermally expansive material than the head connected to one boss and to each of said skirt portions, :1 second transverse st rut connecting the other boss with only one of the skirt portions and being continuous with said first mentioned strut.

6. A piston for an internal combustion engine comprising a head, wrist pin bosses rigidly connected thereto. a circumferentially compressible skirt having oppositely disposed working faces, and a skirt supporting element extending between the boss elements and the central zone of each working face, said skirt supporting element having opposed ends that each terminate in the same quadrant in which portions of the skirt are relatively circumferentially yieldable.

7. A piston for an internal combustion engine comprising a head, a pair of depending wrist pin bosses integral therewith, a separately formed circuniferentially compressible skirt having oppositely disposed working faces, and a skirt supporting element having a pair of spaced struts secured to said wrist pin bosses, one of said struts being secured to the inner Walls of both of said Working faces and the other of said struts being secured to the inner wall of only one of said working faces, said last mentioned strut terminating adjacent the quadrant in which portions of the skirt are relatively circumferentially yieldable.

8. A piston for an internal combustion engine comprising a head, a pair of depending wrist pin bosses rigidly secured thereto, a pair of opposed skirt bearing sections circumferentially separated from said head, circumferential portions at the open end of said piston interconnecting said sections, one of said section interconnecting portions being formed with a slit to render said sections circumferentially compressible, and a skirt supporting element extending between the boss elements and the central zone of each section, said supporting element having opposedends that each terminate in the same quadrant in which said slit is formed.

9. A piston for an internal combustion engine comprising a head,-a pair of depending wrist pin bosses rigidly secured thereto, a pair of opposed skirt bearing sections circulnferentially separated from said head, circumferential portions at the open end of said piston interconnecting said sections, one of said section interconnecting portions being formed with a slit to render said sections circumferentially compressible, a resilient bridge formed on said last mentioned interconnecting portion and bridging said slit to control the expansion and compression of said sections, and a skirt supporting element extending between the boss elements and the central zone of each section, said supporting element having opposed ends that each terminate in the same quadrant in which said slit is formed.

10. A piston comprising a head having depending wrist pin bosses, a circumferentially compressible skirt circumferentially separated from said head having an explosion thrust face and a compression thrust face, and a skirt supporting element having a pair of strut portions secured to the central zone of the wall of said explosion thrust face and to said Wrist pin bosses, one of said strut portions also being secured to the central zone of the wall of said compression thrust face. 11. A piston comprising a head having depending wrist pin bosses, a circumferentially coinpresssible skirt circumferentially separated from said head having an explosion thrust face and a compression thrust face, and a skirt supporting element having a pair of strut portions secured to the central zone of the wall of said explosion thrust face and to said wrist pin bosses, one of said strut portions also being secured to the central zone of the Wall of said compression thrust face, the metal of said skirt and Wrist pin bosses being cast around the secured portions of said supporting element to rigidly embed the same.

In testimony whereof I afiix my signature.

WILLIAM C. MCCOY. 

